1. Technical Field
The present invention relates to thermoelectric conversion elements, pyroelectric light detection devices, and electronic apparatuses.
2. Related Art
Among the known light detection devices is a thermal light detection device including thermal photodetectors arranged in a two-dimensional array along two orthogonal axial directions, each thermal photodetector including, on a substrate, a thermal light detection element having a light absorptive film, and a support member supporting the thermal light detection element (JP-A-2011-153851).
The thermal light detection element of JP-A-2011-153851 above includes a capacitor in which a ferroelectric film, which is a pyroelectric material capable of converting thermal energy into electric energy, is sandwiched between a first electrode and a second electrode. JP-A-2011-153851 above describes, as an example of the ferroelectric film, a film of lead zirconate titanate (PZT, Pb(Zi,Ti)O3), which can be formed by sol-gel, sputtering, MOCVD, or the like. Although PZT is a good pyroelectric material, PZT is considered to be environmentally unfriendly because it contains Pb (lead).
JP-T-2006-518836 describes a pyroelectric sensor system including a scene element having a ferroelectric layer which does not contain Pb (lead). JP-T-2006-518836 states that the ferroelectric layer is selected from strontium bismuth tantalate (SBT), barium bismuth tantalate, and lanthanum bismuth tantalate.
JP-T-2006-518836 above describes SBT as an example material included in the ferroelectric layer. SBT has a lower polarization retention rate than that of PZT. Therefore, when the scene element including an SBT-based ferroelectric material is applied to a pyroelectric sensor system, it is desirable to extract thermal energy received by the scene element as electric energy while maintaining polarization by applying a voltage to the scene element. Therefore, the application of a voltage to the scene element during reading of the pyroelectric sensor system is likely to increase noise, which makes it difficult to allow the pyroelectric sensor system to have high sensitivity.